PTH 000084.31 – MFWD Speed Not Available or Condition Exists

PTH 000084.31 (PTH 84.31)

Code: 000084.31

Shortcode: 84.31


This fault code indicates that the MFWD speed signal is either missing or out of the operating range while the cruise control is engaged. This could be due to sensor issues, wiring problems, or malfunctions in the hydrostatic control unit.


When this error occurs, the MFWD system may be disabled or not function correctly, potentially impacting the vehicle’s traction and stability during cruise control operation.


Inspect MFWD Engagement Sensing Switch (S40):

  • Ensure the switch is operating correctly.
  • Check for any signs of damage or wear.
  • Verify that all electrical connections are secure.

Test Power Train Hydrostatic Control Unit (PTH):

  • Run diagnostics on the control unit to detect any faults.
  • Confirm that all connections to the control unit are tight and free from corrosion.

Check Wiring and Connections:

  • Inspect the wiring harness for damage or loose connections related to the MFWD speed sensor.
  • Repair or replace any damaged wiring as necessary.

Verify Sensor Operation:

  • Test the MFWD speed sensor to confirm it is working within the specified parameters.
  • Replace the sensor if necessary.

Update Control Software:

  • Make sure the control unit software is up-to-date to incorporate any recent fixes or enhancements.

Consult Technical Support:

  • If the issue persists after completing these steps, seek further assistance from technical support.

Monitor System Performance:

  • After implementing the corrections, monitor the MFWD system to ensure normal operation resumes and that the fault does not recur.


Routine maintenance and checks of the MFWD system and sensors can help avoid such faults. Environmental factors such as dirt, debris, or extreme temperatures should also be considered when troubleshooting sensor issues.

Control Units: John Deere

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